1. Field of the Invention
The present invention relates to a piano action device for electronic keyboard musical instruments such as the electronic piano and organ and, more particularly, it relates to a piano action device by which the player can feel as if he or she were playing the acoustic piano even though he or she is playing the electronic keyboard musical instrument in fact.
2. Description of the Related Art
When a key is depressed in the acoustic piano, the force applied to the key is transmitted to a hammer through a wippen and a jack, and the hammer is thus swung to beat a string to create a musical sound. At the first step of depressing the key, therefore, load applied to the finger of the player becomes quickly heavy because of the reaction force of the wippen etc. but it becomes quickly light at the middle step because the hammer is made free.
In the case of the electronic keyboard musical instruments such as the electronic piano, however, any of musical sounds is created by the switch operation which is made operative when the corresponding key is depressed by the player. Therefore, the feeling of the player obtained when he or she depresses the keys of electronic keyboard musical instruments is quite different from his or her feeling obtained when he or she depresses the keys of the acoustic piano.
In the case of a conventional electronic keyboard musical instrument disclosed, for example, in published and unexamined Japanese Patent Application No. 50-153914 (which corresponds to U.S. Pat. No. 3,903,780), published and unexamined Japanese Utility Model Application Nos. 61-124098 and -206978 (which correspond to U.S. Pat. No. 4,723,471), a predetermined load is applied to a key when this key is depressed, thereby enabling the player to feel as if he or she were depressing the key of the acoustic piano.
When a key of the acoustic piano is depressed and its touch becomes quickly light on the way of its key stroke, the corresponding hammer beats the corresponding string to generate a musical sound. In the case of the above-mentioned electronic keyboard musical instruments, however, the key touch of each of the keys does not change quickly until the key makes the corresponding switch operative at the final of its key stroke, because the switches are directly operated by the keys. When quick and light depressions are applied to the keys of the conventional electronic keyboard musical instruments, therefore, it sometimes happens that some of the keys are not depressed enough to make the corresponding switches operative.
Even in the case of those electronic keyboard musical instruments which include first and second switches arranged for every key to achieve touch response function, the same trouble as described above is caused. When a key of the electronic keyboard musical instrument of this type is depressed, the first and second switches are successively made operative with a time difference (t). When the second switch is made operative, key-on data is supplied to a sound source means to generate a musical sound, while touch response data which corresponds to the time difference (t) (key-depressing speed), more specifically, data for determining musical sound parameters such as the sound volume and tone color of the musical sound generated from the sound source, which corresponds to the keydepressing speed, is also supplied to the sound source means.
The two switches are made operative directly by their corresponding key. When quick and light depressions are applied to the keys, therefore, it sometimes happens that the first switches of some keys are put on, while leaving the second switches of these keys off. As the result, those musical sounds which correspond to these unoperated keys are not created even though the keys are depressed.
Published and unexamined Japanese Patent Application No. 63-128397, published and examined Japanese Utility Model Application No. 63-33239, and U.S. Pat. No. 3,634,593 disclose another electronic keyboard musical instrument wherein hammer arms are freely swingably arranged under the keyboard chassis to apply action load to keys, and they are swung by depressing the keys to push their corresponding switches which are attached to the keyboard chassis to detect touch response data.
Key touch or depress feeling substantially similar to that obtained when keys of the acoustic piano are depressed by fingers can be obtained while playing the electronic keyboard musical instrument. In addition, the switches for detecting touch response data can be surely put on by the inertia of their swinging corresponding hammer arms, even when depressing of their keys are not sufficient. If the keys are not moved to the last of their stroke but depressed only by a certain distance, therefore, musical sounds which correspond to the depressed keys can be surely generated. Even when quick and light depressions are applied to the keys of this electronic keyboard musical instrument. Therefore, musical sounds which correspond to the depressed keys can be created, as seen in the case of the acoustic piano.
When keys are strongly depressed in the case of the conventional electronic keyboard musical instruments, however, their hammers cannot follow but swing prior to displacements of depressed keys. This causes action load, which is applied to the keys by their hammers, to be instantly released from the key at a certain point in the key stroke. The player is bewildered at this instant because the depression force for the depressed key becomes quickly light.